prosperon/scripts/particle.js

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var emitter = {};
emitter.particles = {};
emitter.life = 10;
emitter.scale = 1;
emitter.grow_for = 0;
emitter.spawn_timer = 0;
emitter.pps = 0;
emitter.color = Color.white;
emitter.draw = function()
{
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var pars = Object.values(this.particles);
if (pars.length === 0) return;
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render.use_shader(this.shader);
render.use_mat(this);
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render.make_particle_ssbo(pars, this.ssbo);
render.draw(this.shape, this.ssbo, pars.length);
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}
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emitter.kill = function()
{
emitters.remove(this);
}
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var std_step = function(p)
{
if (p.time < this.grow_for) {
var s = Math.lerp(0, this.scale, p.time/this.grow_for);
p.transform.scale = [s,s,s];
}
else if (p.time > (p.life - this.shrink_for)) {
var s = Math.lerp(0,this.scale,(p.life-p.time)/this.shrink_for);
p.transform.scale=[s,s,s];
} else
p.transform.scale = [this.scale,this.scale,this.scale];
}
emitter.step_hook = std_step;
emitter.spawn = function(t)
{
t ??= this.transform;
var par = this.dead.shift();
if (par) {
par.body.pos = t.pos;
par.transform.scale = [this.scale,this.scale,this.scale];
this.particles[par.id] = par;
par.time = 0;
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this.spawn_hook?.(par);
return;
}
par = {
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transform: os.make_transform(),
life: this.life,
time: 0,
color: this.color
};
par.body = os.make_body(par.transform);
par.body.pos = t.pos;
par.transform.scale = [this.scale,this.scale,this.scale];
par.id = prosperon.guid();
this.particles[par.id] = par;
this.spawn_hook(par);
}
emitter.step = function(dt)
{
// update spawning particles
if (this.on && this.pps > 0) {
this.spawn_timer += dt;
var pp = 1/this.pps;
while (this.spawn_timer > pp) {
this.spawn_timer -= pp;
this.spawn();
}
}
// update all particles
for (var p of Object.values(this.particles)) {
p.time += dt;
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this.step_hook?.(p);
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if (p.time >= p.life) {
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this.die_hook?.(p);
this.dead.push(this.particles[p.id]);
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delete this.particles[p.id];
}
}
}
emitter.burst = function(count, t) {
for (var i = 0; i < count; i++) this.spawn(t);
}
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var emitters = [];
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var make_emitter = function()
{
var e = Object.create(emitter);
e.ssbo = render.make_textssbo();
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e.shape = shape.centered_quad;
e.shader = "shaders/baseparticle.cg";
e.dead = [];
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emitters.push(e);
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return e;
}
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function update_emitters(dt)
{
for (var e of emitters)
e.step(dt);
}
function draw_emitters()
{
for (var e of emitters) e.draw();
}
return {make_emitter, update_emitters, draw_emitters};